/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.j2objc.annotations.RetainedWith;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Collection;
import java.util.Comparator;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.RandomAccess;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.Spliterator;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
import java.util.stream.Stream;
import javax.annotation.Nullable;

/**
 * Synchronized collection views. The returned synchronized collection views are serializable if the
 * backing collection and the mutex are serializable.
 *
 * <p>
 * If {@code null} is passed as the {@code mutex} parameter to any of this class's top-level methods
 * or inner class constructors, the created object uses itself as the synchronization mutex.
 *
 * <p>
 * This class should be used by other collection classes only.
 *
 * @author Mike Bostock
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
final class Synchronized {
    private Synchronized() {}

    static class SynchronizedObject implements Serializable {
        final Object delegate;
        final Object mutex;

        SynchronizedObject(Object delegate, @Nullable Object mutex) {
            this.delegate = checkNotNull(delegate);
            this.mutex = (mutex == null) ? this : mutex;
        }

        Object delegate() {
            return delegate;
        }

        // No equals and hashCode; see ForwardingObject for details.

        @Override
        public String toString() {
            synchronized (mutex) {
                return delegate.toString();
            }
        }

        // Serialization invokes writeObject only when it's private.
        // The SynchronizedObject subclasses don't need a writeObject method since
        // they don't contain any non-transient member variables, while the
        // following writeObject() handles the SynchronizedObject members.

        @GwtIncompatible // java.io.ObjectOutputStream
        private void writeObject(ObjectOutputStream stream) throws IOException {
            synchronized (mutex) {
                stream.defaultWriteObject();
            }
        }

        @GwtIncompatible // not needed in emulated source
        private static final long serialVersionUID = 0;
    }

    private static <E> Collection<E> collection(Collection<E> collection, @Nullable Object mutex) {
        return new SynchronizedCollection<E>(collection, mutex);
    }

    @VisibleForTesting
    static class SynchronizedCollection<E> extends SynchronizedObject implements Collection<E> {
        private SynchronizedCollection(Collection<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @SuppressWarnings("unchecked")
        @Override
        Collection<E> delegate() {
            return (Collection<E>) super.delegate();
        }

        @Override
        public boolean add(E e) {
            synchronized (mutex) {
                return delegate().add(e);
            }
        }

        @Override
        public boolean addAll(Collection<? extends E> c) {
            synchronized (mutex) {
                return delegate().addAll(c);
            }
        }

        @Override
        public void clear() {
            synchronized (mutex) {
                delegate().clear();
            }
        }

        @Override
        public boolean contains(Object o) {
            synchronized (mutex) {
                return delegate().contains(o);
            }
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            synchronized (mutex) {
                return delegate().containsAll(c);
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized (mutex) {
                return delegate().isEmpty();
            }
        }

        @Override
        public Iterator<E> iterator() {
            return delegate().iterator(); // manually synchronized
        }

        @Override
        public Spliterator<E> spliterator() {
            synchronized (mutex) {
                return delegate().spliterator();
            }
        }

        @Override
        public Stream<E> stream() {
            synchronized (mutex) {
                return delegate().stream();
            }
        }

        @Override
        public Stream<E> parallelStream() {
            synchronized (mutex) {
                return delegate().parallelStream();
            }
        }

        @Override
        public void forEach(Consumer<? super E> action) {
            synchronized (mutex) {
                delegate().forEach(action);
            }
        }

        @Override
        public boolean remove(Object o) {
            synchronized (mutex) {
                return delegate().remove(o);
            }
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            synchronized (mutex) {
                return delegate().removeAll(c);
            }
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            synchronized (mutex) {
                return delegate().retainAll(c);
            }
        }

        @Override
        public boolean removeIf(Predicate<? super E> filter) {
            synchronized (mutex) {
                return delegate().removeIf(filter);
            }
        }

        @Override
        public int size() {
            synchronized (mutex) {
                return delegate().size();
            }
        }

        @Override
        public Object[] toArray() {
            synchronized (mutex) {
                return delegate().toArray();
            }
        }

        @Override
        public <T> T[] toArray(T[] a) {
            synchronized (mutex) {
                return delegate().toArray(a);
            }
        }

        private static final long serialVersionUID = 0;
    }

    @VisibleForTesting
    static <E> Set<E> set(Set<E> set, @Nullable Object mutex) {
        return new SynchronizedSet<E>(set, mutex);
    }

    static class SynchronizedSet<E> extends SynchronizedCollection<E> implements Set<E> {

        SynchronizedSet(Set<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        Set<E> delegate() {
            return (Set<E>) super.delegate();
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized (mutex) {
                return delegate().equals(o);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return delegate().hashCode();
            }
        }

        private static final long serialVersionUID = 0;
    }

    private static <E> SortedSet<E> sortedSet(SortedSet<E> set, @Nullable Object mutex) {
        return new SynchronizedSortedSet<E>(set, mutex);
    }

    static class SynchronizedSortedSet<E> extends SynchronizedSet<E> implements SortedSet<E> {
        SynchronizedSortedSet(SortedSet<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        SortedSet<E> delegate() {
            return (SortedSet<E>) super.delegate();
        }

        @Override
        public Comparator<? super E> comparator() {
            synchronized (mutex) {
                return delegate().comparator();
            }
        }

        @Override
        public SortedSet<E> subSet(E fromElement, E toElement) {
            synchronized (mutex) {
                return sortedSet(delegate().subSet(fromElement, toElement), mutex);
            }
        }

        @Override
        public SortedSet<E> headSet(E toElement) {
            synchronized (mutex) {
                return sortedSet(delegate().headSet(toElement), mutex);
            }
        }

        @Override
        public SortedSet<E> tailSet(E fromElement) {
            synchronized (mutex) {
                return sortedSet(delegate().tailSet(fromElement), mutex);
            }
        }

        @Override
        public E first() {
            synchronized (mutex) {
                return delegate().first();
            }
        }

        @Override
        public E last() {
            synchronized (mutex) {
                return delegate().last();
            }
        }

        private static final long serialVersionUID = 0;
    }

    private static <E> List<E> list(List<E> list, @Nullable Object mutex) {
        return (list instanceof RandomAccess) ? new SynchronizedRandomAccessList<E>(list, mutex)
                : new SynchronizedList<E>(list, mutex);
    }

    private static class SynchronizedList<E> extends SynchronizedCollection<E> implements List<E> {
        SynchronizedList(List<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        List<E> delegate() {
            return (List<E>) super.delegate();
        }

        @Override
        public void add(int index, E element) {
            synchronized (mutex) {
                delegate().add(index, element);
            }
        }

        @Override
        public boolean addAll(int index, Collection<? extends E> c) {
            synchronized (mutex) {
                return delegate().addAll(index, c);
            }
        }

        @Override
        public E get(int index) {
            synchronized (mutex) {
                return delegate().get(index);
            }
        }

        @Override
        public int indexOf(Object o) {
            synchronized (mutex) {
                return delegate().indexOf(o);
            }
        }

        @Override
        public int lastIndexOf(Object o) {
            synchronized (mutex) {
                return delegate().lastIndexOf(o);
            }
        }

        @Override
        public ListIterator<E> listIterator() {
            return delegate().listIterator(); // manually synchronized
        }

        @Override
        public ListIterator<E> listIterator(int index) {
            return delegate().listIterator(index); // manually synchronized
        }

        @Override
        public E remove(int index) {
            synchronized (mutex) {
                return delegate().remove(index);
            }
        }

        @Override
        public E set(int index, E element) {
            synchronized (mutex) {
                return delegate().set(index, element);
            }
        }

        @Override
        public void replaceAll(UnaryOperator<E> operator) {
            synchronized (mutex) {
                delegate().replaceAll(operator);
            }
        }

        @Override
        public void sort(Comparator<? super E> c) {
            synchronized (mutex) {
                delegate().sort(c);
            }
        }

        @Override
        public List<E> subList(int fromIndex, int toIndex) {
            synchronized (mutex) {
                return list(delegate().subList(fromIndex, toIndex), mutex);
            }
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized (mutex) {
                return delegate().equals(o);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return delegate().hashCode();
            }
        }

        private static final long serialVersionUID = 0;
    }

    private static class SynchronizedRandomAccessList<E> extends SynchronizedList<E> implements RandomAccess {
        SynchronizedRandomAccessList(List<E> list, @Nullable Object mutex) {
            super(list, mutex);
        }

        private static final long serialVersionUID = 0;
    }

    static <E> Multiset<E> multiset(Multiset<E> multiset, @Nullable Object mutex) {
        if (multiset instanceof SynchronizedMultiset || multiset instanceof ImmutableMultiset) {
            return multiset;
        }
        return new SynchronizedMultiset<E>(multiset, mutex);
    }

    private static class SynchronizedMultiset<E> extends SynchronizedCollection<E> implements Multiset<E> {
        transient Set<E> elementSet;
        transient Set<Entry<E>> entrySet;

        SynchronizedMultiset(Multiset<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        Multiset<E> delegate() {
            return (Multiset<E>) super.delegate();
        }

        @Override
        public int count(Object o) {
            synchronized (mutex) {
                return delegate().count(o);
            }
        }

        @Override
        public int add(E e, int n) {
            synchronized (mutex) {
                return delegate().add(e, n);
            }
        }

        @Override
        public int remove(Object o, int n) {
            synchronized (mutex) {
                return delegate().remove(o, n);
            }
        }

        @Override
        public int setCount(E element, int count) {
            synchronized (mutex) {
                return delegate().setCount(element, count);
            }
        }

        @Override
        public boolean setCount(E element, int oldCount, int newCount) {
            synchronized (mutex) {
                return delegate().setCount(element, oldCount, newCount);
            }
        }

        @Override
        public Set<E> elementSet() {
            synchronized (mutex) {
                if (elementSet == null) {
                    elementSet = typePreservingSet(delegate().elementSet(), mutex);
                }
                return elementSet;
            }
        }

        @Override
        public Set<Entry<E>> entrySet() {
            synchronized (mutex) {
                if (entrySet == null) {
                    entrySet = typePreservingSet(delegate().entrySet(), mutex);
                }
                return entrySet;
            }
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized (mutex) {
                return delegate().equals(o);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return delegate().hashCode();
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <K, V> Multimap<K, V> multimap(Multimap<K, V> multimap, @Nullable Object mutex) {
        if (multimap instanceof SynchronizedMultimap || multimap instanceof ImmutableMultimap) {
            return multimap;
        }
        return new SynchronizedMultimap<K, V>(multimap, mutex);
    }

    private static class SynchronizedMultimap<K, V> extends SynchronizedObject implements Multimap<K, V> {
        transient Set<K> keySet;
        transient Collection<V> valuesCollection;
        transient Collection<Map.Entry<K, V>> entries;
        transient Map<K, Collection<V>> asMap;
        transient Multiset<K> keys;

        @SuppressWarnings("unchecked")
        @Override
        Multimap<K, V> delegate() {
            return (Multimap<K, V>) super.delegate();
        }

        SynchronizedMultimap(Multimap<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        public int size() {
            synchronized (mutex) {
                return delegate().size();
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized (mutex) {
                return delegate().isEmpty();
            }
        }

        @Override
        public boolean containsKey(Object key) {
            synchronized (mutex) {
                return delegate().containsKey(key);
            }
        }

        @Override
        public boolean containsValue(Object value) {
            synchronized (mutex) {
                return delegate().containsValue(value);
            }
        }

        @Override
        public boolean containsEntry(Object key, Object value) {
            synchronized (mutex) {
                return delegate().containsEntry(key, value);
            }
        }

        @Override
        public Collection<V> get(K key) {
            synchronized (mutex) {
                return typePreservingCollection(delegate().get(key), mutex);
            }
        }

        @Override
        public boolean put(K key, V value) {
            synchronized (mutex) {
                return delegate().put(key, value);
            }
        }

        @Override
        public boolean putAll(K key, Iterable<? extends V> values) {
            synchronized (mutex) {
                return delegate().putAll(key, values);
            }
        }

        @Override
        public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
            synchronized (mutex) {
                return delegate().putAll(multimap);
            }
        }

        @Override
        public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
            synchronized (mutex) {
                return delegate().replaceValues(key, values); // copy not synchronized
            }
        }

        @Override
        public boolean remove(Object key, Object value) {
            synchronized (mutex) {
                return delegate().remove(key, value);
            }
        }

        @Override
        public Collection<V> removeAll(Object key) {
            synchronized (mutex) {
                return delegate().removeAll(key); // copy not synchronized
            }
        }

        @Override
        public void clear() {
            synchronized (mutex) {
                delegate().clear();
            }
        }

        @Override
        public Set<K> keySet() {
            synchronized (mutex) {
                if (keySet == null) {
                    keySet = typePreservingSet(delegate().keySet(), mutex);
                }
                return keySet;
            }
        }

        @Override
        public Collection<V> values() {
            synchronized (mutex) {
                if (valuesCollection == null) {
                    valuesCollection = collection(delegate().values(), mutex);
                }
                return valuesCollection;
            }
        }

        @Override
        public Collection<Map.Entry<K, V>> entries() {
            synchronized (mutex) {
                if (entries == null) {
                    entries = typePreservingCollection(delegate().entries(), mutex);
                }
                return entries;
            }
        }

        @Override
        public void forEach(BiConsumer<? super K, ? super V> action) {
            synchronized (mutex) {
                delegate().forEach(action);
            }
        }

        @Override
        public Map<K, Collection<V>> asMap() {
            synchronized (mutex) {
                if (asMap == null) {
                    asMap = new SynchronizedAsMap<K, V>(delegate().asMap(), mutex);
                }
                return asMap;
            }
        }

        @Override
        public Multiset<K> keys() {
            synchronized (mutex) {
                if (keys == null) {
                    keys = multiset(delegate().keys(), mutex);
                }
                return keys;
            }
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized (mutex) {
                return delegate().equals(o);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return delegate().hashCode();
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <K, V> ListMultimap<K, V> listMultimap(ListMultimap<K, V> multimap, @Nullable Object mutex) {
        if (multimap instanceof SynchronizedListMultimap || multimap instanceof ImmutableListMultimap) {
            return multimap;
        }
        return new SynchronizedListMultimap<K, V>(multimap, mutex);
    }

    private static class SynchronizedListMultimap<K, V> extends SynchronizedMultimap<K, V>
            implements ListMultimap<K, V> {
        SynchronizedListMultimap(ListMultimap<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        ListMultimap<K, V> delegate() {
            return (ListMultimap<K, V>) super.delegate();
        }

        @Override
        public List<V> get(K key) {
            synchronized (mutex) {
                return list(delegate().get(key), mutex);
            }
        }

        @Override
        public List<V> removeAll(Object key) {
            synchronized (mutex) {
                return delegate().removeAll(key); // copy not synchronized
            }
        }

        @Override
        public List<V> replaceValues(K key, Iterable<? extends V> values) {
            synchronized (mutex) {
                return delegate().replaceValues(key, values); // copy not synchronized
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <K, V> SetMultimap<K, V> setMultimap(SetMultimap<K, V> multimap, @Nullable Object mutex) {
        if (multimap instanceof SynchronizedSetMultimap || multimap instanceof ImmutableSetMultimap) {
            return multimap;
        }
        return new SynchronizedSetMultimap<K, V>(multimap, mutex);
    }

    private static class SynchronizedSetMultimap<K, V> extends SynchronizedMultimap<K, V> implements SetMultimap<K, V> {
        transient Set<Map.Entry<K, V>> entrySet;

        SynchronizedSetMultimap(SetMultimap<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        SetMultimap<K, V> delegate() {
            return (SetMultimap<K, V>) super.delegate();
        }

        @Override
        public Set<V> get(K key) {
            synchronized (mutex) {
                return set(delegate().get(key), mutex);
            }
        }

        @Override
        public Set<V> removeAll(Object key) {
            synchronized (mutex) {
                return delegate().removeAll(key); // copy not synchronized
            }
        }

        @Override
        public Set<V> replaceValues(K key, Iterable<? extends V> values) {
            synchronized (mutex) {
                return delegate().replaceValues(key, values); // copy not synchronized
            }
        }

        @Override
        public Set<Map.Entry<K, V>> entries() {
            synchronized (mutex) {
                if (entrySet == null) {
                    entrySet = set(delegate().entries(), mutex);
                }
                return entrySet;
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <K, V> SortedSetMultimap<K, V> sortedSetMultimap(SortedSetMultimap<K, V> multimap, @Nullable Object mutex) {
        if (multimap instanceof SynchronizedSortedSetMultimap) {
            return multimap;
        }
        return new SynchronizedSortedSetMultimap<K, V>(multimap, mutex);
    }

    private static class SynchronizedSortedSetMultimap<K, V> extends SynchronizedSetMultimap<K, V>
            implements SortedSetMultimap<K, V> {
        SynchronizedSortedSetMultimap(SortedSetMultimap<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        SortedSetMultimap<K, V> delegate() {
            return (SortedSetMultimap<K, V>) super.delegate();
        }

        @Override
        public SortedSet<V> get(K key) {
            synchronized (mutex) {
                return sortedSet(delegate().get(key), mutex);
            }
        }

        @Override
        public SortedSet<V> removeAll(Object key) {
            synchronized (mutex) {
                return delegate().removeAll(key); // copy not synchronized
            }
        }

        @Override
        public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
            synchronized (mutex) {
                return delegate().replaceValues(key, values); // copy not synchronized
            }
        }

        @Override
        public Comparator<? super V> valueComparator() {
            synchronized (mutex) {
                return delegate().valueComparator();
            }
        }

        private static final long serialVersionUID = 0;
    }

    private static <E> Collection<E> typePreservingCollection(Collection<E> collection, @Nullable Object mutex) {
        if (collection instanceof SortedSet) {
            return sortedSet((SortedSet<E>) collection, mutex);
        }
        if (collection instanceof Set) {
            return set((Set<E>) collection, mutex);
        }
        if (collection instanceof List) {
            return list((List<E>) collection, mutex);
        }
        return collection(collection, mutex);
    }

    private static <E> Set<E> typePreservingSet(Set<E> set, @Nullable Object mutex) {
        if (set instanceof SortedSet) {
            return sortedSet((SortedSet<E>) set, mutex);
        } else {
            return set(set, mutex);
        }
    }

    private static class SynchronizedAsMapEntries<K, V> extends SynchronizedSet<Map.Entry<K, Collection<V>>> {
        SynchronizedAsMapEntries(Set<Map.Entry<K, Collection<V>>> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        public Iterator<Map.Entry<K, Collection<V>>> iterator() {
            // Must be manually synchronized.
            return new TransformedIterator<Map.Entry<K, Collection<V>>, Map.Entry<K, Collection<V>>>(super.iterator()) {
                @Override
                Map.Entry<K, Collection<V>> transform(final Map.Entry<K, Collection<V>> entry) {
                    return new ForwardingMapEntry<K, Collection<V>>() {
                        @Override
                        protected Map.Entry<K, Collection<V>> delegate() {
                            return entry;
                        }

                        @Override
                        public Collection<V> getValue() {
                            return typePreservingCollection(entry.getValue(), mutex);
                        }
                    };
                }
            };
        }

        // See Collections.CheckedMap.CheckedEntrySet for details on attacks.

        @Override
        public Object[] toArray() {
            synchronized (mutex) {
                return ObjectArrays.toArrayImpl(delegate());
            }
        }

        @Override
        public <T> T[] toArray(T[] array) {
            synchronized (mutex) {
                return ObjectArrays.toArrayImpl(delegate(), array);
            }
        }

        @Override
        public boolean contains(Object o) {
            synchronized (mutex) {
                return Maps.containsEntryImpl(delegate(), o);
            }
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            synchronized (mutex) {
                return Collections2.containsAllImpl(delegate(), c);
            }
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized (mutex) {
                return Sets.equalsImpl(delegate(), o);
            }
        }

        @Override
        public boolean remove(Object o) {
            synchronized (mutex) {
                return Maps.removeEntryImpl(delegate(), o);
            }
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            synchronized (mutex) {
                return Iterators.removeAll(delegate().iterator(), c);
            }
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            synchronized (mutex) {
                return Iterators.retainAll(delegate().iterator(), c);
            }
        }

        private static final long serialVersionUID = 0;
    }

    @VisibleForTesting
    static <K, V> Map<K, V> map(Map<K, V> map, @Nullable Object mutex) {
        return new SynchronizedMap<K, V>(map, mutex);
    }

    private static class SynchronizedMap<K, V> extends SynchronizedObject implements Map<K, V> {
        transient Set<K> keySet;
        transient Collection<V> values;
        transient Set<Map.Entry<K, V>> entrySet;

        SynchronizedMap(Map<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @SuppressWarnings("unchecked")
        @Override
        Map<K, V> delegate() {
            return (Map<K, V>) super.delegate();
        }

        @Override
        public void clear() {
            synchronized (mutex) {
                delegate().clear();
            }
        }

        @Override
        public boolean containsKey(Object key) {
            synchronized (mutex) {
                return delegate().containsKey(key);
            }
        }

        @Override
        public boolean containsValue(Object value) {
            synchronized (mutex) {
                return delegate().containsValue(value);
            }
        }

        @Override
        public Set<Map.Entry<K, V>> entrySet() {
            synchronized (mutex) {
                if (entrySet == null) {
                    entrySet = set(delegate().entrySet(), mutex);
                }
                return entrySet;
            }
        }

        @Override
        public void forEach(BiConsumer<? super K, ? super V> action) {
            synchronized (mutex) {
                delegate().forEach(action);
            }
        }

        @Override
        public V get(Object key) {
            synchronized (mutex) {
                return delegate().get(key);
            }
        }

        @Override
        public V getOrDefault(Object key, V defaultValue) {
            synchronized (mutex) {
                return delegate().getOrDefault(key, defaultValue);
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized (mutex) {
                return delegate().isEmpty();
            }
        }

        @Override
        public Set<K> keySet() {
            synchronized (mutex) {
                if (keySet == null) {
                    keySet = set(delegate().keySet(), mutex);
                }
                return keySet;
            }
        }

        @Override
        public V put(K key, V value) {
            synchronized (mutex) {
                return delegate().put(key, value);
            }
        }

        @Override
        public V putIfAbsent(K key, V value) {
            synchronized (mutex) {
                return delegate().putIfAbsent(key, value);
            }
        }

        @Override
        public boolean replace(K key, V oldValue, V newValue) {
            synchronized (mutex) {
                return delegate().replace(key, oldValue, newValue);
            }
        }

        @Override
        public V replace(K key, V value) {
            synchronized (mutex) {
                return delegate().replace(key, value);
            }
        }

        @Override
        public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
            synchronized (mutex) {
                return delegate().computeIfAbsent(key, mappingFunction);
            }
        }

        @Override
        public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
            synchronized (mutex) {
                return delegate().computeIfPresent(key, remappingFunction);
            }
        }

        @Override
        public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
            synchronized (mutex) {
                return delegate().compute(key, remappingFunction);
            }
        }

        @Override
        public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
            synchronized (mutex) {
                return delegate().merge(key, value, remappingFunction);
            }
        }

        @Override
        public void putAll(Map<? extends K, ? extends V> map) {
            synchronized (mutex) {
                delegate().putAll(map);
            }
        }

        @Override
        public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
            synchronized (mutex) {
                delegate().replaceAll(function);
            }
        }

        @Override
        public V remove(Object key) {
            synchronized (mutex) {
                return delegate().remove(key);
            }
        }

        @Override
        public boolean remove(Object key, Object value) {
            synchronized (mutex) {
                return delegate().remove(key, value);
            }
        }

        @Override
        public int size() {
            synchronized (mutex) {
                return delegate().size();
            }
        }

        @Override
        public Collection<V> values() {
            synchronized (mutex) {
                if (values == null) {
                    values = collection(delegate().values(), mutex);
                }
                return values;
            }
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized (mutex) {
                return delegate().equals(o);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return delegate().hashCode();
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <K, V> SortedMap<K, V> sortedMap(SortedMap<K, V> sortedMap, @Nullable Object mutex) {
        return new SynchronizedSortedMap<K, V>(sortedMap, mutex);
    }

    static class SynchronizedSortedMap<K, V> extends SynchronizedMap<K, V> implements SortedMap<K, V> {

        SynchronizedSortedMap(SortedMap<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        SortedMap<K, V> delegate() {
            return (SortedMap<K, V>) super.delegate();
        }

        @Override
        public Comparator<? super K> comparator() {
            synchronized (mutex) {
                return delegate().comparator();
            }
        }

        @Override
        public K firstKey() {
            synchronized (mutex) {
                return delegate().firstKey();
            }
        }

        @Override
        public SortedMap<K, V> headMap(K toKey) {
            synchronized (mutex) {
                return sortedMap(delegate().headMap(toKey), mutex);
            }
        }

        @Override
        public K lastKey() {
            synchronized (mutex) {
                return delegate().lastKey();
            }
        }

        @Override
        public SortedMap<K, V> subMap(K fromKey, K toKey) {
            synchronized (mutex) {
                return sortedMap(delegate().subMap(fromKey, toKey), mutex);
            }
        }

        @Override
        public SortedMap<K, V> tailMap(K fromKey) {
            synchronized (mutex) {
                return sortedMap(delegate().tailMap(fromKey), mutex);
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <K, V> BiMap<K, V> biMap(BiMap<K, V> bimap, @Nullable Object mutex) {
        if (bimap instanceof SynchronizedBiMap || bimap instanceof ImmutableBiMap) {
            return bimap;
        }
        return new SynchronizedBiMap<K, V>(bimap, mutex, null);
    }

    @VisibleForTesting
    static class SynchronizedBiMap<K, V> extends SynchronizedMap<K, V> implements BiMap<K, V>, Serializable {
        private transient Set<V> valueSet;
        @RetainedWith
        private transient BiMap<V, K> inverse;

        private SynchronizedBiMap(BiMap<K, V> delegate, @Nullable Object mutex, @Nullable BiMap<V, K> inverse) {
            super(delegate, mutex);
            this.inverse = inverse;
        }

        @Override
        BiMap<K, V> delegate() {
            return (BiMap<K, V>) super.delegate();
        }

        @Override
        public Set<V> values() {
            synchronized (mutex) {
                if (valueSet == null) {
                    valueSet = set(delegate().values(), mutex);
                }
                return valueSet;
            }
        }

        @Override
        public V forcePut(K key, V value) {
            synchronized (mutex) {
                return delegate().forcePut(key, value);
            }
        }

        @Override
        public BiMap<V, K> inverse() {
            synchronized (mutex) {
                if (inverse == null) {
                    inverse = new SynchronizedBiMap<V, K>(delegate().inverse(), mutex, this);
                }
                return inverse;
            }
        }

        private static final long serialVersionUID = 0;
    }

    private static class SynchronizedAsMap<K, V> extends SynchronizedMap<K, Collection<V>> {
        transient Set<Map.Entry<K, Collection<V>>> asMapEntrySet;
        transient Collection<Collection<V>> asMapValues;

        SynchronizedAsMap(Map<K, Collection<V>> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        public Collection<V> get(Object key) {
            synchronized (mutex) {
                Collection<V> collection = super.get(key);
                return (collection == null) ? null : typePreservingCollection(collection, mutex);
            }
        }

        @Override
        public Set<Map.Entry<K, Collection<V>>> entrySet() {
            synchronized (mutex) {
                if (asMapEntrySet == null) {
                    asMapEntrySet = new SynchronizedAsMapEntries<K, V>(delegate().entrySet(), mutex);
                }
                return asMapEntrySet;
            }
        }

        @Override
        public Collection<Collection<V>> values() {
            synchronized (mutex) {
                if (asMapValues == null) {
                    asMapValues = new SynchronizedAsMapValues<V>(delegate().values(), mutex);
                }
                return asMapValues;
            }
        }

        @Override
        public boolean containsValue(Object o) {
            // values() and its contains() method are both synchronized.
            return values().contains(o);
        }

        private static final long serialVersionUID = 0;
    }

    private static class SynchronizedAsMapValues<V> extends SynchronizedCollection<Collection<V>> {
        SynchronizedAsMapValues(Collection<Collection<V>> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        public Iterator<Collection<V>> iterator() {
            // Must be manually synchronized.
            return new TransformedIterator<Collection<V>, Collection<V>>(super.iterator()) {
                @Override
                Collection<V> transform(Collection<V> from) {
                    return typePreservingCollection(from, mutex);
                }
            };
        }

        private static final long serialVersionUID = 0;
    }

    @GwtIncompatible // NavigableSet
    @VisibleForTesting
    static class SynchronizedNavigableSet<E> extends SynchronizedSortedSet<E> implements NavigableSet<E> {
        SynchronizedNavigableSet(NavigableSet<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        NavigableSet<E> delegate() {
            return (NavigableSet<E>) super.delegate();
        }

        @Override
        public E ceiling(E e) {
            synchronized (mutex) {
                return delegate().ceiling(e);
            }
        }

        @Override
        public Iterator<E> descendingIterator() {
            return delegate().descendingIterator(); // manually synchronized
        }

        transient NavigableSet<E> descendingSet;

        @Override
        public NavigableSet<E> descendingSet() {
            synchronized (mutex) {
                if (descendingSet == null) {
                    NavigableSet<E> dS = Synchronized.navigableSet(delegate().descendingSet(), mutex);
                    descendingSet = dS;
                    return dS;
                }
                return descendingSet;
            }
        }

        @Override
        public E floor(E e) {
            synchronized (mutex) {
                return delegate().floor(e);
            }
        }

        @Override
        public NavigableSet<E> headSet(E toElement, boolean inclusive) {
            synchronized (mutex) {
                return Synchronized.navigableSet(delegate().headSet(toElement, inclusive), mutex);
            }
        }

        @Override
        public E higher(E e) {
            synchronized (mutex) {
                return delegate().higher(e);
            }
        }

        @Override
        public E lower(E e) {
            synchronized (mutex) {
                return delegate().lower(e);
            }
        }

        @Override
        public E pollFirst() {
            synchronized (mutex) {
                return delegate().pollFirst();
            }
        }

        @Override
        public E pollLast() {
            synchronized (mutex) {
                return delegate().pollLast();
            }
        }

        @Override
        public NavigableSet<E> subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
            synchronized (mutex) {
                return Synchronized.navigableSet(delegate().subSet(fromElement, fromInclusive, toElement, toInclusive),
                        mutex);
            }
        }

        @Override
        public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
            synchronized (mutex) {
                return Synchronized.navigableSet(delegate().tailSet(fromElement, inclusive), mutex);
            }
        }

        @Override
        public SortedSet<E> headSet(E toElement) {
            return headSet(toElement, false);
        }

        @Override
        public SortedSet<E> subSet(E fromElement, E toElement) {
            return subSet(fromElement, true, toElement, false);
        }

        @Override
        public SortedSet<E> tailSet(E fromElement) {
            return tailSet(fromElement, true);
        }

        private static final long serialVersionUID = 0;
    }

    @GwtIncompatible // NavigableSet
    static <E> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet, @Nullable Object mutex) {
        return new SynchronizedNavigableSet<E>(navigableSet, mutex);
    }

    @GwtIncompatible // NavigableSet
    static <E> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
        return navigableSet(navigableSet, null);
    }

    @GwtIncompatible // NavigableMap
    static <K, V> NavigableMap<K, V> navigableMap(NavigableMap<K, V> navigableMap) {
        return navigableMap(navigableMap, null);
    }

    @GwtIncompatible // NavigableMap
    static <K, V> NavigableMap<K, V> navigableMap(NavigableMap<K, V> navigableMap, @Nullable Object mutex) {
        return new SynchronizedNavigableMap<K, V>(navigableMap, mutex);
    }

    @GwtIncompatible // NavigableMap
    @VisibleForTesting
    static class SynchronizedNavigableMap<K, V> extends SynchronizedSortedMap<K, V> implements NavigableMap<K, V> {

        SynchronizedNavigableMap(NavigableMap<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        NavigableMap<K, V> delegate() {
            return (NavigableMap<K, V>) super.delegate();
        }

        @Override
        public Entry<K, V> ceilingEntry(K key) {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().ceilingEntry(key), mutex);
            }
        }

        @Override
        public K ceilingKey(K key) {
            synchronized (mutex) {
                return delegate().ceilingKey(key);
            }
        }

        transient NavigableSet<K> descendingKeySet;

        @Override
        public NavigableSet<K> descendingKeySet() {
            synchronized (mutex) {
                if (descendingKeySet == null) {
                    return descendingKeySet = Synchronized.navigableSet(delegate().descendingKeySet(), mutex);
                }
                return descendingKeySet;
            }
        }

        transient NavigableMap<K, V> descendingMap;

        @Override
        public NavigableMap<K, V> descendingMap() {
            synchronized (mutex) {
                if (descendingMap == null) {
                    return descendingMap = navigableMap(delegate().descendingMap(), mutex);
                }
                return descendingMap;
            }
        }

        @Override
        public Entry<K, V> firstEntry() {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().firstEntry(), mutex);
            }
        }

        @Override
        public Entry<K, V> floorEntry(K key) {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().floorEntry(key), mutex);
            }
        }

        @Override
        public K floorKey(K key) {
            synchronized (mutex) {
                return delegate().floorKey(key);
            }
        }

        @Override
        public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
            synchronized (mutex) {
                return navigableMap(delegate().headMap(toKey, inclusive), mutex);
            }
        }

        @Override
        public Entry<K, V> higherEntry(K key) {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().higherEntry(key), mutex);
            }
        }

        @Override
        public K higherKey(K key) {
            synchronized (mutex) {
                return delegate().higherKey(key);
            }
        }

        @Override
        public Entry<K, V> lastEntry() {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().lastEntry(), mutex);
            }
        }

        @Override
        public Entry<K, V> lowerEntry(K key) {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().lowerEntry(key), mutex);
            }
        }

        @Override
        public K lowerKey(K key) {
            synchronized (mutex) {
                return delegate().lowerKey(key);
            }
        }

        @Override
        public Set<K> keySet() {
            return navigableKeySet();
        }

        transient NavigableSet<K> navigableKeySet;

        @Override
        public NavigableSet<K> navigableKeySet() {
            synchronized (mutex) {
                if (navigableKeySet == null) {
                    return navigableKeySet = Synchronized.navigableSet(delegate().navigableKeySet(), mutex);
                }
                return navigableKeySet;
            }
        }

        @Override
        public Entry<K, V> pollFirstEntry() {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().pollFirstEntry(), mutex);
            }
        }

        @Override
        public Entry<K, V> pollLastEntry() {
            synchronized (mutex) {
                return nullableSynchronizedEntry(delegate().pollLastEntry(), mutex);
            }
        }

        @Override
        public NavigableMap<K, V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
            synchronized (mutex) {
                return navigableMap(delegate().subMap(fromKey, fromInclusive, toKey, toInclusive), mutex);
            }
        }

        @Override
        public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
            synchronized (mutex) {
                return navigableMap(delegate().tailMap(fromKey, inclusive), mutex);
            }
        }

        @Override
        public SortedMap<K, V> headMap(K toKey) {
            return headMap(toKey, false);
        }

        @Override
        public SortedMap<K, V> subMap(K fromKey, K toKey) {
            return subMap(fromKey, true, toKey, false);
        }

        @Override
        public SortedMap<K, V> tailMap(K fromKey) {
            return tailMap(fromKey, true);
        }

        private static final long serialVersionUID = 0;
    }

    @GwtIncompatible // works but is needed only for NavigableMap
    private static <K, V> Entry<K, V> nullableSynchronizedEntry(@Nullable Entry<K, V> entry, @Nullable Object mutex) {
        if (entry == null) {
            return null;
        }
        return new SynchronizedEntry<K, V>(entry, mutex);
    }

    @GwtIncompatible // works but is needed only for NavigableMap
    private static class SynchronizedEntry<K, V> extends SynchronizedObject implements Entry<K, V> {

        SynchronizedEntry(Entry<K, V> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @SuppressWarnings("unchecked") // guaranteed by the constructor
        @Override
        Entry<K, V> delegate() {
            return (Entry<K, V>) super.delegate();
        }

        @Override
        public boolean equals(Object obj) {
            synchronized (mutex) {
                return delegate().equals(obj);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return delegate().hashCode();
            }
        }

        @Override
        public K getKey() {
            synchronized (mutex) {
                return delegate().getKey();
            }
        }

        @Override
        public V getValue() {
            synchronized (mutex) {
                return delegate().getValue();
            }
        }

        @Override
        public V setValue(V value) {
            synchronized (mutex) {
                return delegate().setValue(value);
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <E> Queue<E> queue(Queue<E> queue, @Nullable Object mutex) {
        return (queue instanceof SynchronizedQueue) ? queue : new SynchronizedQueue<E>(queue, mutex);
    }

    private static class SynchronizedQueue<E> extends SynchronizedCollection<E> implements Queue<E> {

        SynchronizedQueue(Queue<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        Queue<E> delegate() {
            return (Queue<E>) super.delegate();
        }

        @Override
        public E element() {
            synchronized (mutex) {
                return delegate().element();
            }
        }

        @Override
        public boolean offer(E e) {
            synchronized (mutex) {
                return delegate().offer(e);
            }
        }

        @Override
        public E peek() {
            synchronized (mutex) {
                return delegate().peek();
            }
        }

        @Override
        public E poll() {
            synchronized (mutex) {
                return delegate().poll();
            }
        }

        @Override
        public E remove() {
            synchronized (mutex) {
                return delegate().remove();
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <E> Deque<E> deque(Deque<E> deque, @Nullable Object mutex) {
        return new SynchronizedDeque<E>(deque, mutex);
    }

    private static final class SynchronizedDeque<E> extends SynchronizedQueue<E> implements Deque<E> {

        SynchronizedDeque(Deque<E> delegate, @Nullable Object mutex) {
            super(delegate, mutex);
        }

        @Override
        Deque<E> delegate() {
            return (Deque<E>) super.delegate();
        }

        @Override
        public void addFirst(E e) {
            synchronized (mutex) {
                delegate().addFirst(e);
            }
        }

        @Override
        public void addLast(E e) {
            synchronized (mutex) {
                delegate().addLast(e);
            }
        }

        @Override
        public boolean offerFirst(E e) {
            synchronized (mutex) {
                return delegate().offerFirst(e);
            }
        }

        @Override
        public boolean offerLast(E e) {
            synchronized (mutex) {
                return delegate().offerLast(e);
            }
        }

        @Override
        public E removeFirst() {
            synchronized (mutex) {
                return delegate().removeFirst();
            }
        }

        @Override
        public E removeLast() {
            synchronized (mutex) {
                return delegate().removeLast();
            }
        }

        @Override
        public E pollFirst() {
            synchronized (mutex) {
                return delegate().pollFirst();
            }
        }

        @Override
        public E pollLast() {
            synchronized (mutex) {
                return delegate().pollLast();
            }
        }

        @Override
        public E getFirst() {
            synchronized (mutex) {
                return delegate().getFirst();
            }
        }

        @Override
        public E getLast() {
            synchronized (mutex) {
                return delegate().getLast();
            }
        }

        @Override
        public E peekFirst() {
            synchronized (mutex) {
                return delegate().peekFirst();
            }
        }

        @Override
        public E peekLast() {
            synchronized (mutex) {
                return delegate().peekLast();
            }
        }

        @Override
        public boolean removeFirstOccurrence(Object o) {
            synchronized (mutex) {
                return delegate().removeFirstOccurrence(o);
            }
        }

        @Override
        public boolean removeLastOccurrence(Object o) {
            synchronized (mutex) {
                return delegate().removeLastOccurrence(o);
            }
        }

        @Override
        public void push(E e) {
            synchronized (mutex) {
                delegate().push(e);
            }
        }

        @Override
        public E pop() {
            synchronized (mutex) {
                return delegate().pop();
            }
        }

        @Override
        public Iterator<E> descendingIterator() {
            synchronized (mutex) {
                return delegate().descendingIterator();
            }
        }

        private static final long serialVersionUID = 0;
    }

    static <R, C, V> Table<R, C, V> table(Table<R, C, V> table, Object mutex) {
        return new SynchronizedTable<R, C, V>(table, mutex);
    }

    private static final class SynchronizedTable<R, C, V> extends SynchronizedObject implements Table<R, C, V> {

        SynchronizedTable(Table<R, C, V> delegate, Object mutex) {
            super(delegate, mutex);
        }

        @SuppressWarnings("unchecked")
        @Override
        Table<R, C, V> delegate() {
            return (Table<R, C, V>) super.delegate();
        }

        @Override
        public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
            synchronized (mutex) {
                return delegate().contains(rowKey, columnKey);
            }
        }

        @Override
        public boolean containsRow(@Nullable Object rowKey) {
            synchronized (mutex) {
                return delegate().containsRow(rowKey);
            }
        }

        @Override
        public boolean containsColumn(@Nullable Object columnKey) {
            synchronized (mutex) {
                return delegate().containsColumn(columnKey);
            }
        }

        @Override
        public boolean containsValue(@Nullable Object value) {
            synchronized (mutex) {
                return delegate().containsValue(value);
            }
        }

        @Override
        public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
            synchronized (mutex) {
                return delegate().get(rowKey, columnKey);
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized (mutex) {
                return delegate().isEmpty();
            }
        }

        @Override
        public int size() {
            synchronized (mutex) {
                return delegate().size();
            }
        }

        @Override
        public void clear() {
            synchronized (mutex) {
                delegate().clear();
            }
        }

        @Override
        public V put(@Nullable R rowKey, @Nullable C columnKey, @Nullable V value) {
            synchronized (mutex) {
                return delegate().put(rowKey, columnKey, value);
            }
        }

        @Override
        public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
            synchronized (mutex) {
                delegate().putAll(table);
            }
        }

        @Override
        public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
            synchronized (mutex) {
                return delegate().remove(rowKey, columnKey);
            }
        }

        @Override
        public Map<C, V> row(@Nullable R rowKey) {
            synchronized (mutex) {
                return map(delegate().row(rowKey), mutex);
            }
        }

        @Override
        public Map<R, V> column(@Nullable C columnKey) {
            synchronized (mutex) {
                return map(delegate().column(columnKey), mutex);
            }
        }

        @Override
        public Set<Cell<R, C, V>> cellSet() {
            synchronized (mutex) {
                return set(delegate().cellSet(), mutex);
            }
        }

        @Override
        public Set<R> rowKeySet() {
            synchronized (mutex) {
                return set(delegate().rowKeySet(), mutex);
            }
        }

        @Override
        public Set<C> columnKeySet() {
            synchronized (mutex) {
                return set(delegate().columnKeySet(), mutex);
            }
        }

        @Override
        public Collection<V> values() {
            synchronized (mutex) {
                return collection(delegate().values(), mutex);
            }
        }

        @Override
        public Map<R, Map<C, V>> rowMap() {
            synchronized (mutex) {
                return map(Maps.transformValues(delegate().rowMap(),
                        new com.google.common.base.Function<Map<C, V>, Map<C, V>>() {
                            @Override
                            public Map<C, V> apply(Map<C, V> t) {
                                return map(t, mutex);
                            }
                        }), mutex);
            }
        }

        @Override
        public Map<C, Map<R, V>> columnMap() {
            synchronized (mutex) {
                return map(Maps.transformValues(delegate().columnMap(),
                        new com.google.common.base.Function<Map<R, V>, Map<R, V>>() {
                            @Override
                            public Map<R, V> apply(Map<R, V> t) {
                                return map(t, mutex);
                            }
                        }), mutex);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return delegate().hashCode();
            }
        }

        @Override
        public boolean equals(@Nullable Object obj) {
            if (this == obj) {
                return true;
            }
            synchronized (mutex) {
                return delegate().equals(obj);
            }
        }
    }
}
